Apparatus for use in the determination of the relative humidity of substances

ABSTRACT

The invention relates to an apparatus for use in the determination of weight changes in substances exposed to atmospheres of different relative humidities. The apparatus comprises a cabinet containing a plurality of moistureproof compartments for samples to be tested. Each compartment has a door which can be opened or closed as desired. A fan is provided in each compartment and a common drive means for the fan is located outside the compartments. The operation of the fans is controlled by a timing device.

United States Patent David N. Gore Westhumble, near Dorking, Surrey; Harold C. Wilkinson, Worthing, Sussex, both oi, England 747,388 July 24, 1968 July 20, l97l Beecharn Group Limited inventors Appl No. Filed Patented Assignee APPARATUS FOR usE IN TIIE DETERMINATION or TIIE RELATIVE HUMIDITY or SUBSTANCES 3 Claims, 3 Drawing Figs.

U.S.Cl 312/209, 312/236 lnt.Cl ..A47b77/08, A47f5/08 FieldofSearch 312131.01, I 3L6, 209, 236

[56] References Cited UNITED STATES PATENTS 3,024,076 3/ 1962 Wulfften Palthe .v 3 l 2/236 3,198,163 8/1965 Williams 3l2/3l.l-X" 3,366,432 l/l968 Cramer 312/236 Primary Examiner-Casmir A. Nunberg Attorney-Jacobs and Jacobs A ABSTRACT: The invention relates to an apparatus for use in the determination of weight changes in substances exposed to atmospheres of different relative humidities. The apparatus comprises a cabinet containing a plurality of moistureproof compartments for samples to be tested. Each compartment has a door which can be opened or closed as desired. A fan is provided in each compartment and a common drive means for the fan is located outside the compartments. The operation of the fans is controlled by a timing device.

APPARATUS FOR USE IN THE DETERMINATION OF THE RELATIVE HUMIDITY OF SUBSTANCES BACKGROUND OF THE INVENTION It is frequently important to measure the effect of atmospheres of different relative humidities on substances under test. For example, it is often important to obtain such information in the pharmaceutical industry where in some cases the presence of moisture in a pharmaceutical substance above known limits could result in a loss in the medical potency of the product. .It is frequently necessary to establish the upper limit beyond which the medical potency of the substance will decrease. This is usually done by storing samples of the substances under test in sealed containers at a range of temperatures likely to be encountered in normal practice. The residual potency is then estimated against time. When a moisture specification for a substance has been established in this way, it is necessary to determine the relationship between the moisture contents and the relative humidity so that conditions for handling, packing, and selection of packaging components can be considered in a rational way.

It is an object of the present invention to provide an apparatus which can be used in such tests. Accordingly, the invention provides an apparatus comprising a cabinet containing a plurality of moistureproof compartmentsfor samples to be tested. Each compartment has a door which can be opened or closed as desired. A fan is provided in each compartment and a common drive means for the fans is located outside the compartments. The operation of the fans is controlled by a timing device.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. I is a front view of an apparatus according to the invention,

FIG. 2 is a diagrammatic transverse sectional view and FIG. 3 is a rear view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the illustrated embodiment of the invention, an apparatus for use in determining weight changes in substances exposed to atmospheres of various relative humidities comprises a cabinet 1 which is mounted on casters 2 for ease of movement.

The cabinet 1 contains a plurality of independent transparent window 6, conveniently of plastics material. A

sealing strip (not visual in the drawings) of resilient foam plastics or other material runs round the inside of the door surround and cooperates with a facing resilient tubing 7 attached to a cooperating face of the compartment. The compartment can be made of a noncorrosive metal of low gauge, preferably covered by a rubber based paint. The doors have hinges 9 which are preferably of the offset type to assist in obtaining a good seal when the doors are closed. The compartments are provided with shelves l0, conveniently two for each compartment, and these shelves have perforations 4 and are preferably of a plastics material. The compartment can have a plurality of shelf supports 12 so that the shelves can be arranged at differing heights.

Each compartment 3 contains a fan l3 for circulating air through the compartment as desired. These fans 13 are mounted adjacent the rear walls 3r of the compartments and are rotated by drive shafts 14 which extend through the backwalls of the compartments. The shafts 14 extend through the backwalls of the compartments in greased nylon bearings 15 which provide a moistureproof seal. The portions of the drive shafts 14 outside the compartments are provided with chain wheels 16. A common chain drive 17 passes over all these chain wheels 16 so that the fans 13 can be rotated in unison. The chain drive 17 is driven by a variable speed electric motor 18. The rear walls Sr of the compartments 3 are spaced from the adjacent wall of the cabinet so that the chain wheels 16 and chain drive 17 are located in the space between the compartments and the cabinet. The operation of the electric drive motor 18 is controlled by a time switch 19 so that the fans can be driven for predetermined periods.

In operation, samples are placed in containers, conveniently in the form of weighing bottles. These containers have lids which provide an effective moisture proof seal, but which are removed during the period of exposure in the cabinets, and

. replaced immediately after removal from the cabinet prior to 30 weighing at suitable intervals. Various standard humidities are established in the compartments by placing on the floor of each an open vessel, e.g. a glass or plastic dish or tray containing the appropriate salt solution.

The cabinet, being mounted on casters, is mobile and easily moved in any desired location for purposes of storage or weighing requirements.

What we claim is:

1. An apparatus for use in the determination of weight changes in substances exposed to atmospheres of different relative humidities comprising a cabinet comprising a plurality of moistureproof compartments for samples to be tested, each compartment having a door which can be opened or closed as desired; a fan in each compartment; a common drive means for the fans, the said drive means being located outside the compartments; and a timing device controlling the operation of the fans.

2. An apparatus as claimed in claim 1 wherein each fan is mounted on a drive shaft extending through a bearing in a wall of the compartment opposite its door, a drive wheel is mounted on each drive shaft outside the compartment and a common drive chain is passed over each'of the drive wheels and is movable by an electric motor.

3. An apparatus as claimed in claim 2 comprising in addition a plurality of perforated shelves in each compartment on which samples to be tested can be supported.

Patent No. 3,594,054 Dated July 20, 1971 Inventor-( David N. Gore It is certified that and that said Letters Pate error appears in the aboveidentified patent nt are hereby corrected as shown below:

Kindly insert the follo wing applicaton priority of which was claimed:

-- British Application No. 34599/67, filed July 27, 1967 Signed and sealed this L th day of January 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents 

2. An apparatus as claimed in claim 1 wherein each fan is mounted on a drive shaft extending through a bearing in a wall of the compartment opposite its door, a drive wheel is mounted on each drive shaft outside the compartment and a common drive chain is passed over each of the drive wheels and is movable by an electric motor.
 3. An apparatus as claimed in claim 2 comprising in addition a plurality of perforated shelves in each compartment on which samples to be tested can be supported. 